WASHINGTON (Reuters) - U.S. President-elect Donald Trump should not scrap a nuclear deal between Iran and world powers but should take the nation to task for its "destabilizing activities" in the Middle East, said a former senior Saudi official.

Gulf powers watched with alarm as U.S. President Barack Obama forged a deal with its top regional foe over Iran's nuclear program last year and warned it would embolden Tehran's pursuit of regional hegemony in part through support for proxy groups fuelling regional conflicts.

Trump, who triumphed in the U.S. election this week, has said he would dismantle the nuclear deal agreed last year, although he has made other contradictory statements on the accord. Iran denies ever having considered developing atomic weapons.

"I don't think he should scrap it. It's been worked on for many years and the general consensus in the world, not just the United States, is that it has achieved an objective, which is a 15-year hiatus in the program that Iran embarked on to develop nuclear weapons," Prince Turki al-Faisal, a former Saudi intelligence chief and ex-ambassador to Washington and London said on Thursday.

"To scrap that willy-nilly as it were will have ramifications, and I don't know if something else can be put in its place to guarantee that Iran will not go that route if the agreement is scrapped," he said at a think-tank event in Washington.

Prince Turki said he would like to see if the deal could become a "stepping stone" to a more permanent program "to prevent proliferation through the establishment of a zone free of weapons of mass destruction in the Middle East."

Prince Turki does not presently hold any official position in the Saudi leadership, and he emphasized that he was speaking in a personal capacity. His views are described by insiders as often reflecting those of the kingdom's top princes and as influential in Riyadh foreign policy circles.

Prince Turki also said Trump should admonish Iran for its "very adventurous and very destabilizing activities" in the Middle East.

Iran, the dominant Shi'ite Muslim power, supports Syrian President Bashar al-Assad and has dispatched teams to Syria to gather intelligence and train Syrian forces. As a rival of Sunni Saudi Arabia, Iran has fought decades of sectarian proxy wars in Syria, Lebanon, Iraq and Yemen.

"I would like to see President Trump marshal American public opinion and American government activity to challenge that view of Iran that it can license itself to interference," he said.